1. Field of the Invention
The present invention relates generally to an implantable prosthesis and, more particularly, to a prosthetic device having an electrode carrier.
2. Related Art
There are several electrical stimulation devices that use an electrical signal to activate nerve or muscle fibers in a patient to stimulate an activity. A prosthetic hearing device or implant is an example of such a device that is used to aid patients who have a hearing deficiency. Prosthetic hearing devices apply a stimulating signal to the cochlea of the ear to stimulate hearing.
Prosthetic hearing devices need to be rigid enough to maintain their structural integrity and their position, so that electrodes in the device can remain in place against nerve endings. However, insertion or implantation of such prosthetic devices can be uncomfortable and potentially damaging to the delicate physical structures of a body. Therefore, it is desirable to be able to insert the prosthetic hearing device in a manner that does not damage delicate physical structures while maintaining the structural integrity of the device.
CA 1323731 (Societe Anonyme MXM) describes an electrode-carrier device able to be implanted in the cochlea so as to electrically stimulate the nervus acusticus. It is directed to the problem of aligning the electrodes in the electrode carrier against the nerve ends in the cochlear. The cochlear, being a helicoidal tube, twists any electrode carrier being inserted into it and so the insertion raises alignment issues. To achieve the aim of aligning the electrodes against the nerve ends, the electrode carrier of this disclosure includes a mechanical discontinuity extending over only one part of the cross-section, dissymmetric to the axis of the carrier and close to the extremity of the carrier. The mechanical discontinuity is limited to the lateral and medial sides of the electrode carrier.
EP 0 002 068 B1 (Hansen et al) describes an electrode carrier in which the part to be accommodated in the cochlear has an eigencurvature in the longitudinal direction of the support. During implantation, the carrier is forced to assume a temporary condition of curvature. After implantation, the carrier is transferred from the temporary curvature to a permanent curvature by mechanical means. Therefore, the material used for the carrier must be a material with mechanical memory.